Oxidation of sulfur dioxid and catalyst therefor



have used UNITED STATES PATENT OFFICE.

FRANZ SLAHA. AND HANS WOLF, OF LUDWIGSHAFEN-ON-THE-RHINE, GERMANY,

ABSIGNORS '10 GENERAL CHEMICAL COMPANY, OF NEW YORK, N. Y., A COB- POBATION OF NEW YORK.

OXIDATION OI SULFUR DIOXID AND CATALYST THEREFOR.

No Drawing.

To all whom it may concern I Be it known that we,'F'RANz SLAMA and HANS llVoLF, citizens, respectively, of Austria and Germany, both residing at Ludwigshafen-on-the-Rhine, Germany, have invented certain new and useful Improvements in Oxidation of Sulfur Dioxid and Catalyst Therefor, of which the following is a specification.

This invention relates to the production and use of a commercially efficient catalyst or contact substance for the production of sulfuric anhydrid from sulfur dioxid. and ox gen.

11 United States Patent No. 687,834 is described a substance of the general class of vanadium catalysts; however, the product of that patent doestnot convert more than 84% of the sulfur dioxid into sulfuric anhydrid, which makes it useless for commercial purposes.

Now, we have discovered a new vanadium catalyst which effects conversion of sulfur dioxid and oxygen into sulfuric anhydrid to an extent of 96% and over of the contained sulfur dioxid.

Broadly considered, this invention consists in providing a carrier for a vanadium containing substance, which carrier has a fineness of division very muchgreater than that of similar carriers heretofore employed,

So far as we are aware no vanadium catalysts have been used or described in which the carrier was less than 5000 microns in maximum dimension. As such carriers we ground pumice, kieselguhr, precipitated sil1cic-acid,'stannic oxid, or stannic hydroxid, or mixtures of all or any of them; we prefer to employ these materials of adsgree of fineness such that the individual particles do not exceed twenty microns and are preferably in the neighborhood of one micron in diameter, although we are not limit ed to degrees of fineness falling within such limits, as coarser particles of carrier may be used and a largeincrease 'of conversion still be obtained. When we speak in our claims of a carrier very fin y divided we mean to indicate a carrier in t e here defined finely divided form, that is to say so much finer than those hitherto employed for vanadium catalysts that the catalyst of which it forms a part produces or is suited to produce, a commercially substantial in- Speclfication of Letters Patent.

more stable.

Patented Mar. 8, 1921.

Application filed October a, 1914. Serial No. 885,807.

crease "of conversion over those hitherto known; but not so coarse that it is not capable of granulation. Particles of carrier should, therefore, not have a diameter larger than sixty (60) microns;

In developing this feature of the invention wehave discovered several collateral or subsidiary new steps in the production of a suitable vanadium catalyst; for example, the addition of potassium hydrate or sodium hydrate, or the carbonate or the sulfate or the nitrate of these, in order to protect the new catalgst from deterioratin lIl catalytic activity; nally, the removal 0? hygroscopic properties by heating such catalyst in the presence of air and in the absenceof sulfur dioxid. A The form in which we use the vanadium may be that of vanadic oxid or of ammonium vanadate, or of potassium vanadate, with or without, as the case may be, the addition of potassium or sodium hydrate, carbonate, sulfate, or nitrate, so as to stabilize the catalyst by overcoming any hygroscopic properties which it may possess. I

It is possible, and in fact likely, that the potassium or sodium hydrate may lose its water upon heating and be present in the catalyst in the form of potash or soda, When we speak in ,our claims of potash we intend to cover potassium oxid and potassium hydrate as the case may be, as well as the other equivalent substances referred to.

This new catalytic substance, however prepared, may, if occasion requires,- be commingled with a suitable binding'agent and then molded or pressed into any desired shape. The substance may then be treated for sometime in gases containing sulfur dioxid, for instance in burner gases, since this has a binding effect upon the small particles and assists in rendering the catalyst Should the catalyst, after being heated by sulfur dioxid gases, be hygroscopic, this property can be diminished or removed b subseauently heating it in the PIGSBEOG 0 air an in the absence of sulfur dioxi In the following examples we illustrate how this invention can be carried into effect, but we wish to be distinctly understood as not being limited to the precise conditions therein set out, since these may be varied within considerable limits without departlo'ammonia 18 no lon er given off ing from the s irit of this invention while shaped catalytic a cut containin vanadium obtaining the ull benefit and yalue of this in chemical combination distri uted on a invention. The arts are by weight; very finely divided carrier not exceeding Example 1.: ix 200 parts of moist punt-,- sixty microns in diameter ice powder (the grains of which have a (11- 3. As a new composition of matter, a 55 ameter oi one micron) with 14 arts of arm catalytic agent containing vanadic oxid dismonium wanadate; granulate t is mixture tributed on a veryfinely divided carrier not and heat the resulting granular product to exceeding sixty microns in diameter. about 300 C. in the presence 0 air until 4. As a new composition of matter, a

and then catalytic agent containing vanadic oxid and 60 heat to 440 C. in t e Presence of gas conpotash distributed on a Veryfinely divided sulfur dioxid, until carrier not exceeding sixty microns in diamtaining or consisting 0 substantially no further change in the condieter.

tion of the particles takes place. This prod- 5. The improvement in the art of making 15 uct'is now ready for use as a catalyst in" the sulfuric anhydrid which consists in causing 65 production'of sulfuric anhydrid from gases sulfundioxi and oxygen to come into concontaining sulfur dioxid' and oxygen in the tact with a catal tic agent com rising vanausual contact or catalytic process. Any dium in chemica combination istributed on other suitable carrier may be used in place a very finely divided carrier not exceeding of the pumice if in sufficiently finely d1- sixty micron in diameter. 70 vided condition. 6. The improvement in the art of making Example 2'. Mix 316 parts of kieselguhr sulfuric anhydrid which consists in caus- (either as it occurs in nature or after trlting sulfur dioxid and oxygen to come into uration) which may previously have been contact with a catalytic agent comprising 2 heated to a redheat, with an aqueous soluvanadic oxid distributed on a very finely 75 tion of 50 parts ammonium vanadate and 56 divided carrier not exceeding sixty microns parts of potassium hydrate; thereupon in diameter. evaporate off so much of the water that the 7. The improvement in the art of making remainder can be formed into granules; sulfuric anhydrid which consists in causing place this result in a furnace and heat at sulfur dioxid and oxygen to come into con- 80 480 C. with gas containing sulfur diox1d tact with a catalytic afifnt containing vanaand oxygen (such as can be obtained from dic oxid and potash, w ich agent has previa pyrites burner) and then, if desired, conously been heatedin the presence of air and tinue the heatin for some time in a current in the absence of sulfur dioxid. of air; the pro not of this operation is a 8. The improvement in the art ofmaking B5 catalytic agent which is ready for use in a catalytic agent which comprises treating the same manner as the product in 1511- a very finely divided carrier "not exceeding am le 1.

sixty microns in diameter with a salt of he catalyst produced by Examples 1 and vanadic acid and then heating the same in 40 2 is employed for the manufacture of sulthe presence of air and in the absence of 90 furic anhydrid in the usual manner, namely sulfur 'dioxid.

by bringing into contact-with it both sulfur In testimony whereof we have hereunto dioxid and oxygen. set our hands in the presence of two sub- We cla m: scribing witnesses. 1. As a new composition of matter, a FRANZ SLAMA catal tic agent containin vanadium in y chemical combination distm uted on a very HANS WOLF finely divided carrier not exceeding sixty Witnesses: microns'in diameter. H. MERLE Coommn,

'2. As a new composition ofmatter, a ALBERT TAG.

ID'IBCLA'IMER 1,371,004.Fmnz 87mm and Hem Wolf, Ludwig shzll'en-on-the-I i,hine,v Germany. OXIDATION or SULFUR Dxoxm AND CATALYST Tanneron. Patent dated March 8, 1921. Disclaimer filed'April 13, 1934, by the assignee, The General Chemical Company.

Enter its disclaimer to the subject-metter of 7 of said Letters Patent, to

wit. "7. The improvement in the art of naking sulfuric enhyilrid vyhich oonsietejn eausing sulfur dioxid and oxygen to come mto contact nth a catalytic agent eontammg venadic oxid and potash, which agent has previouslybeen heated in the presence of air and in the absence of sulfur dioxid."

Gazette May 8, 1984.] 

